This invention relates to pneumatic tires and, more particularly, to a novel and highly-effective improvement of the tires which are disclosed in U.S. Pat. No. 3,327,753, assigned to the assignee of the present invention.
The reinforcement of such tires comprises a carcass ply of cords, cables or threads that are continuous from bead to bead and that are radial in the sidewalls and oblique in the region of the tread. In the region of the tread the reinforcement comprises, in addition to the oblique portion of the carcass ply, another ply of oblique cords or threads, the latter cords or threads being crossed with respect to the oblique cords or threads of the carcass ply and limited to the region of the tread.
Such a reinforcement is easy to manufacture and offers the advantage of ensuring a continuous connection of the reinforcement of the sidewalls to that of the tread. Furthermore, the sidewalls have the same flexibility as tires with a completely radial carcass--that is, a carcass that is radial from bead to bead. Under certain conditions, the tread of such tires needs additional reinforcement. This is why the patent provides for the reinforcement thereof by the addition of at least one other ply of oblique cords or threads limited to the region of the tread. This addition is possible, however, only after the shaping of the basic reinforcement defined above. On the other hand, the fundamental structure of these tires is extended without difficulty to the use of at least one ply which is continuous from bead to bead but the orientation of the cords or threads of which may differ by as much as 20.degree. from the radial orientation in the sidewalls, while retaining a definitely oblique portion in the region of the tread.